Apparatus for heating liquids



Oct. 30, 1962 w. s. LURING ETAL 3,060,921

APPARATUS FOR HEATING LIQUIDS Original Filed Aug. 12, 1958 EXHAUST GASESWilliam s. Luring Marvin B. Glaser Charles W. Foust Joseph D. SohisInventors Patent Attorney United States Patent Office 3,060,921 PatentedOct. 30, 1962 3,069,921 APPARATUS FOR IEATING LIQUlDS William S. Luring,Elizabeth, Marvin B. Glaser, Plainfield, Charles W. Foust, Berkeley, andJoseph D. Soltis, Elizabeth, N..I., assignors to Esso Research andEngineering Company, a corporation of Delaware Original application Aug.12, 1958, fier. No. 754,651. Divided and this application Dec. 9, 1960,Ser. No. 76,437 1 Claim. (Cl. 126-460) This invention relates toapparatus for heating liquids, especially water. It relates particularlyto such apparatus in which heat transfer to the liquid intended to beultimately heated is effected through indirect thermal contact of thisliquid with an intermediate body of liquid, especially an intermediatebody of water. It relates more particularly to such apparatus in whichheat is trans ferred into the aforementioned intermediate body of liquidby direct mixing therewith of gaseous products of combustion, and itrelates more particularly still to such apparatus of a size and formadapted for installation in dwelling houses.

The present application is a division of co-pending application SerialNo. 754,651, filed in the United States Patent Oflice on August 12,1958.

Oil and gas-fired combustion units are widely used in dwelling houseservice for heating water to be circulated through radiators for spacewarming, and to issue from taps for washing, cooking, and other domesticpurposes. In its usual embodiments, one of these units will com prise afurnace having a burner element, a combustion chamber, and a heattransfer conduit through Which water to be heated is circulated, thisconduit being located in or above the combustion chamber. Above orbeyond the heat transfer conduit is a stack. Hot gaseous products ofcombustion flowing through the combustion chamber sweep over the exposedsurfaces of the conduit, and heat is absorbed by water in this conduitfrom these products. Leaving the conduit region, the products ofcombustion flow up and out the stack.

On an average, the overall efliciency of combustiontype dwelling housewater heating installations is less than 65%. This is largely the resultof low heat absorption efficiency which averages around 72%. While thereis a possibility of improving the absorption efliciency by carefulredesign of burner and combustion chamber elements of water heatingfurnaces within the presently existing general configuration of thesefurnaces, it is considered that there will always be an irreducible heatloss of at least 15% in such furnaces because of stack requirements.This heat must be sacrificed to prevent condensation in the stack, andparticularly to maintain a temperature differential for establishment ofan updraft for a furnace in the basement of a dwelling house, thepractically universal location.

According to this invention, the above-mentioned requirement for heatsacrifice for maintenance of proper stack conditions in water heatingfurnaces is avoided by employing the principle of submerged combustion.Gaseous products of combustion are discharged into a primary water bodybelow the surfaces thereof. Heat transfer takes place from the gaseousproducts to the water body by direct mixing and at a very highvolumetric rate, the gases finally escaping from the water surface.

The primary water body is in indirect thermal contact with and transfersheat to water which is circulated for home heating and domesticpurposes. By appropriate configuration of the apparatus embodiment ofthis invention, the gaseous products of combustion may give up usefulheat to water until they have ben cooled to as low as 100 F. No stack ofany significant height will be needed because the positive driveimparted to the gases entering the primary water body obviates relianceon a draft effect. Further, because of high rates of volumetric heattransfer, the apparatus will be extremely compact and amenable tolocation in other than basement regions.

The nature and substance of this invention may be more clearly perceivedand fully understood by referring to the following description andclaims taken in COI1I1 tion with the accompanying drawing whichrepresents a view in sectional elevation through a heating chambersuitable for use as a component of an apparatus embodiment of thisinvention in which gaseous products of combustion flow upwardly througha flue Within the chamber to enter a water body retained therein. Thechamber also contains coils immersed in the water body, through whichcoils water to be raised in temperature for home heating and domesticpurposes is circulated.

Referring now to the drawing in detail, 66 designates a heating chamberwhich is provided with a roof 68. This roof has an opening about andabove which is mounted a stack member or gas escape conduit 70. In thebottom of chamber 66 there is a central opening through which extendsupwardly a flue 72 from a combustor unit 74 having suitable connectionswherethrough it is supplied with air and fuel. This combustor has awater tight attachment to the bottom of chamber 66 through mountingflange 76. At its upper end flue 72 is provided with a cap 78 which issupported from the flue by means of a horizontal perforated plate 80.

At the bottom of the heating chamber there is a drain line 82. Enteringthe chamber through roof 68 and terminating above flue cap 78 is a line84 wherethrough liquid may be supplied to the heating chamber. This linehas a coiled configuration within gas escape conduit 70. Also withinthis conduit and below the coiled configuration of line 84 there isattached a flared circular member 86 whereby a collector trough regionis formed at the base of the conduit. Leading away through the conduitwall from the trough region there is a drain line 88.

Within the heating chamber there is a water body 90 having a surface 92.This surface is maintained by suitable, well known means at a levelsomewhat if only slightly above perforated plate but below the upper endof flue 72. Immersed in the water body below plate 80 are two pipe coilssurrounding flue 72 and having inlet and outlet lines penetrating thewall of chamber 66. One coil 94 with inlet line 96 and outlet line 98 isintended to carry water to be heated for domestic purposes such aswashing and cooking. The other coil 100 with inlet line 162 and outletline 104 is intended to carry water to be heated for circulation throughroom radiators and snow melting coils.

When combustor 74 is fired, the hot gaseous products of combustionissuing therefrom will rise through and out of flue 72, and then beforced by cap 78 to flow downwardly through the perforations in plate 80to form bubbles in water body whereby this water will be heateddirectly. The water will also be heated to a relatively slight extent byconduction from the hot gases within flue 72 through the flue wall. Onthe other hand, the water surrounding the flue will keep the latterelement relatively cool. As water streams for space heating, snowmelting, and domestic purposes are passed through the coils immersed inwater body 90, they will be raised in temperature by indirect heattransfer from this body.

The bubbles of gaseous products of combustion leaving the perforationsin plate 80' on the underside thereof will finally escape around theedges of flue cap 78 and rise to and through water surface 92. Once freeof this surface, these gaseous products will flow toward and throughconduit 76. In passing through this conduit they will sweep over thesurface of the coiled configuration of line 84 therein, giving up mostof any potentially useful residual heat they may have to water flowingin this line.

It is evident that the gases flowing through conduit 70 and anywaterfrom water body 96 entrained as mist therewith may be cooled so lowthat condensation of certain vapors will take place on the inner surfaceof conduit 70 whereby liquid will be formed with a tendency to run backdown the conduit and fall into the water body. This liquid may well beacidic, and may possibly pick up solid contaminants from the conduitinner surface or otherwise. In any case it had better 'be prevented fromentering water body 99. Accordingly the function of the trough spaceformed in conduit 70 by circular element 86 is that of a sump in whichthis condensate liquid may be collected and from which it may be run oflthrough drain line 8% to an appropriate disposal region.

Solids and unduly acidic water deposited and generated in chamber 66 maybe drained off through line 82 either intermittently or continuously,and replenishment water supplied through makeup line 34. This inflowingwater is directed onto flue cap 7 8. In this way the cap is cooled andthe water absorbs heat which might otherwise be substantially wasted.The inflow of water through line 84 will at least slightly exceed theoutflow through drain 82 to compensate for any evaporation and leakageeffects.

The apparatus embodiment of this invention appearing in the drawing willbe extremely compact in comparison with conventional heating plants usedin residential buildings. Heat absorption efficiencies over 95% havebeen demonstrated in submerged combustion experiments performed in thelaboratory. These eificiencies have been achieved at volumetric heattransfer rates up to 1,200,000 B.t.u./hr./ft.

Put in terms of illustrated apparatus, if water body 90 had a volume of1 ft. it could absorb 1,200,000 B.t.u./hr. from combustion gasesbubbling through it. The Water body would, of course, have to becont-inuously discharging this absorbed heat to some other body ormedium to avoid being boiled away itself. The high volumetric rate ofheat transfer is a feature of this invention at least if not morestartling than its high thermal efiiciency. This high rate means thatsubmerged combustion units for heating liquids will be light in weightas well as compact a characteristic noted already. No expensive,insulated stack of any height will be needed because exhaust gases arepositively forced out of the apparatus. Very quiet operation may beexpected. For these reasons a submerged combustion unit may be locatedin such hitherto unlikely locations for a heating plant as an attic or afirst floor closet wherefrom a small gas escape conduit may be easilyled away.

Although this invention has been described with a certain degree ofparticularity, it is to be understood that the present disclosure hasbeen made only by Way of example and that numerous changes in thedetails of construction and the combination and arrangement of parts maybe resorted to Without departing from the spirit and scope of thisinvention as hereinafter claimed.

What is claimed is:

An apparatus for heating liquids which comprises (1) a heating chamberhaving interior wall surfaces, (2) a first body of liquid Wherewith saidchamber is at least partially filled, (3) a combustor unit, ('4) a fluewherethrough gaseous products of combustion are carried away from saidcombustor extending upwardly into said first body of liquid from saidcombustor, (5) means at least partially immersed in said first body ofliquid whereby products of combustion leaving said flue are required topass through at least part of said first body of liquid as a pluralityof bubble streams, said means including in combination a plate memberextending outwardly from said flue and characterized by a plurality ofperforations and a cap member surmounting said plate member andenclosing the upper end of said flue, the combination of said plate andcap members being characterized by an outer edge region in spacedrelation to said interior wall surfaces of said heating chamber to leavea passage between said region and said surfaces, (6) means whereby asecond body of liquid may be brought into indirect thermal contact withsaid first body of liquid, (7) a conduit extending outwardly from saidheating chamber wherethrough said products of combustion may be finallyexhausted from said chamber, (8) means wherethrough replenishment liquidmay be supplied to maintain said first body of liquid in said chamber,said means being in such spaced relation to said conduit that suchreplenishment liquid passing therethrough will come into indirectthermal contact with said products of combustion passing through saidconduit, and (9) means for gathering and draining away vapors condensedto the liquid state within said conduit and deposited on the innersurfaces thereof.

References Cited in the file of this patent UNITED STATES PATENTS883,407 Jessup Mar. 31, 1908 2,233,675 Narten Mar. 4, 1941 2,376,632Sullivan May 22, 1945 2,810,382 Warren Oct. 22, 1957 2,878,644 Fenn Mar.24, 1959 2,900,975 Northcott Aug. 25, 1959

